Cliffs & Rocky beaches

A breakwater is a coastal structure (usually a rock and rubble mound structure) projecting into the sea that shelters vessels from waves and currents, prevents siltation of a navigation channel, protects a shore area or prevents thermal mixing (e.g. cooling water intakes). A breakwater typically comprises various stone layers and is typically armoured with large armour stone or concrete armour units (an exception are e.g. vertical (caisson) breakwaters). A breakwater can be built at the shoreline or offshore (detached or reef breakwater). This measure is not directly addressed to protect the coast in flood events, but can indirectly stabilize the coast by preventing erosion.

Not all stakeholders are aware or informed about their vulnerability to a changing climate, or flood risk protection. Nor are they aware of the pro-active measures they can take to adapt or deal with climate change. Awareness raising and education programs are therefore important to manage the impacts of climate change, enhance peoples’ capacity to deal with the impacts, and reduce overall vulnerability.

Sharing knowledge in this way can help build safety and resilience, reduce future hazard impacts. Communities and individuals usually want to become partners in this, and the public can be empowered to deal with the impacts and reduce future problems related to flood risk and disaster risk response.

Criel sur Mer is a small town in Normandy in the region of Northern France, known for its stunning coastline of steep chalk cliffs. Erosion of the cliffs in Criel sur Mer is occurring rapidly as a result of climate change but also due to man-made construction works further up the coast. In Criel sur Mer a short piece of land on the coast that is eroding rapidly and several homes built near the sea are threatened by the predicted collapse of the cliff. In particular, a street of homes were faced with immediate danger from erosion. Between 1995 and 2003, the local administration organized the abandonment and demolishment of 14 homes due to imminent risk from natural disaster under the Barnier Law. The adoptive policy was to do nothing against cliff erosion and to demolish and relocate those in immediate threat and compensate them fairly for their lost property.

The beach of Pevensey Bay (UK) is a shingle barrier beach under threat from flooding and coastal erosion. Today, the beach is managed in an adaptive manner developed by Pevensey Coastal Defence, where management activities respond to changes in risk and beach recharge and beach recycling is undertaken.

Coral and oyster reefs are considered to be types of coastal wetlands. As a natural coastal defense they are a buffer for coastlines against waves. Reefs are threatened by rapid environmental change, making it very important to protect and restore reefs.

Coastal and marine environments are usually characterized by beautiful landscapes and rich ecosystems of great importance, offering elements such as rich biodiversity. They also attract human activities such as tourism and industrial uses. However, the co-existence of human activities and natural resources often creates conflicts of use in the coastal zone.

Management policies are an important means of implementing planning in order to minimise, prevent or resolve use conflicts. The development of a coastal and marine spatial planning system presents an opportunity for the implementation of an overall strategy of conservation, sustainability and management to maximise future economic profit.

Flood forecasting is an essential tool for providing people still exposed to risk with advance notice of flooding, in an effort to save life and property.

To minimize the loss of lives and reduce other flood impacts, an area should be evacuated when the depth of standing water due to flooding is already or is expected to become high. Such floods are defined as those which are expected to cause buildings, including residential houses, to be washed away or seriously damaged by the flooding.

The purpose of early warning systems (EWS) is simple. They exist to give advance notice of an impending flood, allowing emergency plans to be put into action. EWS, when used appropriately, can save lives and reduce other adverse impacts.

It is vital to recognize that even after the implementation of non-structural flood mitigation measures residual flood risk will remain. It is of paramount importance to make plans to deal with flood events and their aftermath. This involves multiple activities which can be included as part of a flood emergency plan. In this section there is an overview of the elements central to emergency planning.

Flood risk awareness is the cornerstone of non-structural flood risk management. All actions to minimize the impact of flooding hinge upon stakeholders becoming aware these are both necessary and desirable. Ignorance of flood risk encourages occupation of the floodplain, in the first instance, and can allow appropriate building design practices to fall into disuse. In the event of a flood, the lack of awareness of risk can result in a failure to heed warnings to evacuate, thereby endangering lives.

Cliff stabilization is a coastal management erosion control technique. Generally speaking, the cliffs are stabilised through anchoring (the use of terracing, planting, wiring or concrete supports to hold cliffs in place), smothing the slope, or dewatering (drainage of excess rainwater to reduce water-logging).

Shingle beaches are mobile structures developed in high-energy environments that are very efficient at absorbing and dissipating wave energy. Restoration of shingle beaches on the foreshore can create a more desirable morphological profile that is better able to dissipate wave energy and attenuate storm surge.

Managed realignment is a measure that usually results in the creation of a salt marsh by removing costal protection an allowing for an area previously protected from flooding to become flooded. Managed realignment is a measure dealing with sea level rise and coastal erosion. It is also often a method that replaces hard coastal defense measures with soft coastal landforms. Rather than relying on hard structures for defense, managed realignment depends on natural defenses to absorb or dissipate the force of waves.

To reduce cliff erosion and its consequences – landslide, collapse, falling of rocks – cliff strengthening techniques aim at increasing the strength and overall stability of the slope by minimizing landside pressures.

A breakwater is a coastal structure (usually a rock and rubble mound structure) projecting into the sea that shelters vessels from waves and currents, prevents siltation of a navigation channel, protects a shore area or prevents thermal mixing (e.g. cooling water intakes). A breakwater typically comprises various stone layers and is typically armoured with large armour stone or concrete armour units (an exception are e.g. vertical (caisson) breakwaters). A breakwater can be built at the shoreline or offshore (detached or reef breakwater). This measure is not directly addressed to protect the coast in flood events, but can indirectly stabilize the coast by preventing erosion.

Beach drains comprise perforated land drain pipes buried below the upper beach surface, and connected to a pump and discharge. The concept is based on the principle that sand will tend to accrete if the beach surface is permeable due to an artificially lowered water table. The system is largely buried and therefore has no visual impact.

A seawall or a revetment is a structure made of concrete, masonry or sheet piles, built parallel to the shore at the transition between the beach and the mainland or dune, to protect the inland area against wave action and prevent coastal erosion. Seawalls are usually massive structures designed to resist storm surges.

'Elevation of buildings' and ' Land raising' are two separated measures with the aim to elevate exposed elements.

Moving a building out of the existing flood hazard area is the safest solution among several retrofit-ting methods; however it is also usually the most expensive method (FEMA, 2009). When a community acquires a flood-prone home from the owner, relocation is often applied, as well as demolition of the building. The relocation is not only limited to buildings, it can also be applied to other exposed coastal infrastructure.

Coastal setbacks are an demarcated area where all or certain types of development are prohibited. Coastal setbacks can be measured either as a minimum distance from the shoreline for new buildings or infrastructure facilities, or may state a minimum elevation above sea level for development.  Setbacks determined by distance from the shore are used to combat coastal erosion, while setbacks determined by evaluation are used to control flooding.

Highly dynamic coastal systems (like sandy beaches, dunes or estuaries) might be best managed by not interfering with the natural processes, but instead accepting that change will occur and adapting backshore management accordingly. Key in this approach is a proper monitoring of the processes to analyze and evaluate the changes (for examples at eroding cliffs or dunes). With a proper planning horizon, these changes can be anticipated and with enough room for the environment to involve this can be a very cost-extensive approach.

Artificial reefs are shore parallel rock mound structures set part way down the beach face. They may be long single structures or form a series of reefs extending for some distance alongshore. They are submerged for at least part of the tidal cycle, and are therefore less intrusive on the coastal landscape, have less impact on upper beach longshore processes and add a new intertidal habitat to sandy foreshores.

Groynes are cross-shore structures designed to reduce longshore transport on open beaches or to deflect nearshore currents within an estuary. On an open beach they are normally built as a series to influence a long section of shoreline that has been nourished or is managed by recycling. In an estuary they may be single structures.